This invention relates to the art of coffee makers of the type having a water reservoir within a coffee maker housing and having means within the housing for heating the water obtained from the reservoir and pumping the hot water so as to be discharged into a coffee basket mounted above a coffee decanter.
Some of the prior art coffee makers of this type include those shown in the U.S. Patents to C. J. Hupf, U.S. Pat. No. 3,996,846 and K. H. Bergmann, U.S. Pat. No. 3,987,717. Such coffee makers typically provide a housing including a base and a hood, mounted atop the base, with the base having a coffee decanter support portion extending horizontally therefrom to support a coffee decanter. A body portion extends upwardly from the support portion and terminates in an overhanging hood. The hood provides a means for communicating heated water from a heater, mounted in the base, to be discharged into a coffee basket located below the hood and above a decanter. In such coffee makers, the overhanging hood portion serves mainly as a conduit for the heated water to be discharged into the coffee basket and the upstanding base portion contains a water reservoir so as to provide a vertical column of water to be heated. The water heater is located underneath the reservoir and is typically mounted to the floor of the base portion. The heater is known as a water pump heater and has a riser tube or pump tube which serves as a conduit for discharging heated water from the heat pump upwardly through the water reservoir and then discharged through the overhanging hood portion and into the coffee basket therebelow. In some versions of this type of coffee brewing machine, the coffee basket is slidably secured to the overhanging hood and discharges brewed coffee into a coffee decanter located therebelow on the decanter support. In other types, the coffee basket rests directly on top of the coffee decanter.
Water heated by the pump heater is pumped upwardly through the pump tube a vertical distance corresponding with that from the pump to the overhanging discharge spout. Water to be heated is poured into the coffee maker through a opening on top of the hood so as to fill the water reservoir. In so doing, cold water fills the pump and the riser tube to a height corresponding with the water level in the reservoir. Consequently, when the electric pump heater is turned on and commences its pumping operation, this initial volume or slug of cold water in the pump tube is pushed upwardly through the pump tube to the discharge spout and discharged into the coffee basket. This detracts from the brewing operation since it is desirable that the temperature of the water being discharged into the coffee basket be in the range of about 195.degree. F. to 205.degree. F. A notable problem in the prior art coffee makers of the types referred to above is the height of the pump tube. With the pump being mounted on the bottom of the base the pump tube may well have a height on the order of seven to eight inches measured upwardly from the pump well to the discharge spout. It has been determined that the temperature of the water discharged from the spout into the coffee basket is directly related to the head or height of water in the pump tube. The shorter the pump tube, the higher will be the temperature of the discharged water.